Air Cleaner User Manual

imperative that this be done for certain IBM devices that use the Atape.driver to
ensure proper SysBack function. Failure to do so can render your data
unrecoverable.
Any tapes previously created with “autoload=yes” should be tested for the ability
to recover them. They can only be recovered by resetting “autoload=yes” since the
tape was made that way. The command to set this attribute is: Also, for IBM
devices that have the device driver option “use random mode to emulate auto”,
this must also be set to ’no’. To determine if your device driver has this setting,
issue the command:
chdev -l rmtX -a autoload=no
where X represents your tape drive number.
Also, for IBM devices that have the device driver option “use random mode to
emulate auto”, this must also be set to ’no’. To determine if your device driver has
this setting, issue the command:
lsattr -El rmtX
where X represents your tape drive number. To change this setting, issue the
command:
chdev -l rmtX -a emulate_auto=no
where X represents your tape drive number.
Other Tape Drives
Any tape drive that is recognized by AIX should be usable by SysBack, although
no support can be guaranteed. Most tape drives have at least a 64 Kbyte buffer,
which is the default buffer size that SysBack uses. If you are using a tape drive
that does not have a large buffer, usually resulting in a “write: I/O error” or “illegal
parameter” messages, you might need to reduce the buffer size value SysBack uses
each time a backup is performed. Try using “32” (Kbytes) as the next value, then
“16,”, and so on. If the error continues, either the tape drive or tape media is
defective, or it is not supported by AIX or SysBack.
IBM 7331 8mm Tape Library
If the 7331 8mm Tape Library is installed with 2 tape drives, SysBack backups
usually achieve twice the performance of a single 8mm tape drive when
configured as described in this section.
To configure SysBack and the 7331 library for the best performance, create a
SysBack parallel virtual device containing both tape drives in the unit. Then set the
7331 to “Split Sequential” mode. This allows SysBack to “stripe” the data across
both tape drives, achieving twice the performance, while allowing the 7331 to
change the tapes in each drive as the backup reaches the end of volume.
When in Split-Sequential mode, the 7331 assigns the first, or top, 10 tapes in the
magazine to the top tape drive and the bottom 10 tapes in the magazine to the
bottom tape drive. Note that the SCSI connection to the 7331 library itself is not
used by SysBack, only the SCSI connection to the tape drives themselves.
E-2 IBM Tivoli Storage Manager for System Backup and Recovery: Installation and User’s Guide